Acceleration on a curve [kinematics]

a car is moving forward at 60 km/h [E 45° N], executes a turn and is now moving at 35 km/h [N 80° W]. If the turn takes 8 seconds to complete the turn what is the average acceleration of the car in m/s?

2. Relevant equations

v2 = v1 + a(t)

3. The attempt at a solution

v2 = 35
v1 = 60
t = 8
a = ?

v2 = v1+ a(t)

35km/h = 9.72 m/s
60km/h = 16.6 m/s

35 = 60 + a(8)
35-60 = 8a
a= -3.125m/s

i'm not sure if its right, because don't you accelerate positively when you change direction

a car is moving forward at 60 km/h [E 45° N], executes a turn and is now moving at 35 km/h [N 80° W]. If the turn takes 8 seconds to complete the turn what is the average acceleration of the car in m/s?

2. Relevant equations

v2 = v1 + a(t)

3. The attempt at a solution

v2 = 35
v1 = 60
t = 8
a = ?

v2 = v1+ a(t)

35km/h = 9.72 m/s
60km/h = 16.6 m/s

35 = 60 + a(8)
35-60 = 8a
a= -3.125m/s

i'm not sure if its right, because don't you accelerate positively when you change direction

Welcome to PF.

Remember velocity is a vector. As is acceleration. So ... that means that you might do better to resolve the velocities into their components and then figure the change in velocity by x,y to determine the direction and angle of the average change over the 8 seconds.

ok well based on what you said: split into x and y and find average i came up with this diagram:

http://img132.imageshack.us/img132/3949/diagram.jpg [Broken]

I used the previous values (60), (35) to create the x and y for the purple triangle and finally finding the average speed represented by the "?", i then divided that value by the time (8 seconds) and got my answer. Was my method correct?

ok well based on what you said: split into x and y and find average i came up with this diagram:

http://img132.imageshack.us/img132/3949/diagram.jpg [Broken]

I used the previous values (60), (35) to create the x and y for the purple triangle and finally finding the average speed represented by the "?", i then divided that value by the time (8 seconds) and got my answer. Was my method correct?